Many analytical laboratory instruments make use of a propellor and power shaft to generate internal pressures, densities, torques and forces, all of which, directly or indirectly influence the viscosity of the liquid phase of the test material. Examples of this type of physical phenomenon which may be measured or determined through rheological measuring procedures are the following: flow rate of polymers, surface properties, air bubble entrapment, fiber wetout, and structural integrity of the test sample.
The present inventive method makes usage of a strain transducer. Strain transducers, as such, have long been known in the prior art. However, their usage in the method as set forth herein is believed to be novel.
The most related prior art of which the invention are aware comprises U.S. Pat. No. 3,285,057 (1966) to De Zurik; No. 4,171,647 (1979) to Herrgen; No. 4,445,365 to Jelby; No. 4,352,287 to Orth; No. 4,445,365 (1984) to Selby; No. 4,706,506 (1987) to Lestelle; and United Kingdom Patent No. 1,181,961 (1970) to Brooking.
The above and other prior art are not capable of measuring or responding to all components of torque which are torsionally imparted to the power shaft within the test vessel. More particularly, the prior art does not teach a test method which measures or utilizes both the radial and axial components of torque in the test vessel. The present invention advantageously employs these torque components as a part of an effective test method.